/*
 * Copyright (c) 2018  Wenzhou Institute, University of Chinese Academy of Sciences.
 * See the accompanying Manual for the contributors and the way to cite this work.
 * Comments and suggestions welcome. Please contact
 * Dr. Guanghong Zuo <ghzuo@ucas.ac.cn>
 * 
 * @Author: Dr. Guanghong Zuo
 * @Date: 2016-04-19 11:37:42
 * @Last Modified By: Dr. Guanghong Zuo
 * @Last Modified Time: 2018-07-26 22:01:37
 */

#include "memory.h"

/**
 * Returns the size of physical memory (RAM) in bytes.
 */

size_t getMemorySize(){
#if defined(_WIN32) && (defined(__CYGWIN__) || defined(__CYGWIN32__))
/* Cygwin under Windows. ------------------------------------ */
/* New 64-bit MEMORYSTATUSEX isn't available.  Use old 32.bit */
    MEMORYSTATUS status;
    status.dwLength = sizeof(status);
    GlobalMemoryStatus( &status );
    return (size_t)status.dwTotalPhys;

#elif defined(_WIN32)
/* Windows. ------------------------------------------------- */
/* Use new 64-bit MEMORYSTATUSEX, not old 32-bit MEMORYSTATUS */
    MEMORYSTATUSEX status;
    status.dwLength = sizeof(status);
    GlobalMemoryStatusEx( &status );
    return (size_t)status.ullTotalPhys;

#elif defined(__unix__) || defined(__unix) || defined(unix) || (defined(__APPLE__) && defined(__MACH__))
/* UNIX variants. ------------------------------------------- */
/* Prefer sysctl() over sysconf() except sysctl() HW_REALMEM and HW_PHYSMEM */
#if defined(CTL_HW) && (defined(HW_MEMSIZE) || defined(HW_PHYSMEM64))
    int mib[2];
    mib[0] = CTL_HW;
#if defined(HW_MEMSIZE)
    mib[1] = HW_MEMSIZE;            /* OSX. --------------------- */
#elif defined(HW_PHYSMEM64)
    mib[1] = HW_PHYSMEM64;          /* NetBSD, OpenBSD. --------- */
#endif
    int64_t size = 0;               /* 64-bit */
    size_t len = sizeof( size );
    if ( sysctl( mib, 2, &size, &len, NULL, 0 ) == 0 )
	return (size_t)size;
    return 0L;			/* Failed? */

#elif defined(_SC_AIX_REALMEM)
/* AIX. ----------------------------------------------------- */
    return (size_t)sysconf( _SC_AIX_REALMEM ) * (size_t)1024L;

#elif defined(_SC_PHYS_PAGES) && defined(_SC_PAGESIZE)
/* FreeBSD, Linux, OpenBSD, and Solaris. -------------------- */
    return (size_t)sysconf( _SC_PHYS_PAGES ) *
	(size_t)sysconf( _SC_PAGESIZE );

#elif defined(_SC_PHYS_PAGES) && defined(_SC_PAGE_SIZE)
/* Legacy. -------------------------------------------------- */
    return (size_t)sysconf( _SC_PHYS_PAGES ) *
	(size_t)sysconf( _SC_PAGE_SIZE );

#elif defined(CTL_HW) && (defined(HW_PHYSMEM) || defined(HW_REALMEM))
/* DragonFly BSD, FreeBSD, NetBSD, OpenBSD, and OSX. -------- */
    int mib[2];
    mib[0] = CTL_HW;
#if defined(HW_REALMEM)
    mib[1] = HW_REALMEM;		/* FreeBSD. ----------------- */
#elif defined(HW_PYSMEM)
    mib[1] = HW_PHYSMEM;		/* Others. ------------------ */
#endif
    unsigned int size = 0;		/* 32-bit */
    size_t len = sizeof( size );
    if ( sysctl( mib, 2, &size, &len, NULL, 0 ) == 0 )
	return (size_t)size;
    return 0L;			/* Failed? */
#endif /* sysctl and sysconf variants */

#else
    return 0L;			/* Unknown OS. */
#endif
}
